In Sapan, magnesian raw materials which were formerly obtained from Manchuria and Korea as magnesite and brucite, can now be scarcely obtained from sea water resources, by reacting lime or calcined dolomite powder with sea water, brine or bittern to precipitate magnesium hydroxide.
In the present paper, samples of this sea water magnesium hydroxide were collected from various plants, calcined to light magnesia by heating at 600-800°C for 1-2 hours, and analysed to determine the fact that this sea water magnesia contains pretty large amount of lime, as 5-15% in magnesium hydroxide base or 8-20% in calcined light magnesia base.
Four samples of sea water magnesia thus obtained were tested on their hardening properties as magnesia cement, by mixing with silica sand, kneading with bittern solutions (Bé.22, 25 and 28°), by testing of bending and compressive strengths by the same testing method of the ordinary and mixed Portland cements in the Japanese Industrial Standards, and discussed on this testing results in the following points: (1) the effect of lime content,(2) the effect of mixing silica powder,(3) the effects of concentration and mixing amount of bittern solution., etc.
This study is now being further continued, which will be reported hereafter in the Journal.
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